onnxruntime

Added support for ReduceMean on DNNL EP for CPU and GPU (#7902)

* Added support for ReduceMean on DNNL EP for CPU and GPU

Signed-off-by: Chethan Palangotu Keshava <chethan.palangotu.keshava@intel.com>

* Added fix for a resnet model failure where it was failing to create dst shape for reducemean when it was part of a subgraph with other ops

Signed-off-by: Chethan Palangotu Keshava <chethan.palangotu.keshava@intel.com>

* Removing the DNNL EP from these unit tests. This is in anticipation of two changes:
- DNNL EP unit tests would be added in a different location later on, so addition of EP individually to these tests will not be necessary
- This was causing a memory leak fail in debug build. The bug is in the EP itself and not in the code added for reducemean. The fix for this is in the i/o handling overhaul which will be added later.

* Update reduction_ops_test.cc

Had accidentally deleted a new line. Making sure there are no unnecessary changes in this file